The present invention relates to perfluorinated cyclic ethers and methods of synthesizing them.
"Crown" ethers can be generally defined as macroheterocyclic compounds comprising the repeating unit (--O--CH.sub.2 --CH.sub.2 --). As explained in "Principles and Synthetic Applications in Crown Ether Chemistry," Gokel and Durst, Synthesis 168-184 (1976), which is incorporated in this specification by reference, the name "crown" comes from the appearance of the space filling (CPK) molecular models and the ability of these compounds to "crown" cations by complexation. For example, 15-crown-5 ether can be represented as follows: ##STR1##
Direct fluorination of crown ethers, or any other compound, has presented difficult kinetic and thermodynamic problems in the past. Directly fluorinated crown ethers are unknown because conventional synthesis methods are not available. The highly exothermic nature of direct fluorination reactions has had explosive results in some cases, and has caused many researchers to avoid these reactions altogether.
A different approach, aften referred to as the "La-Mar" direct fluorination process, was developed to overcome these problems. The La-Mar process generally involves blanketing material to be fluorinated in an inert atmosphere. Fluorine gas, or halogen fluorides, are then introduced. This fluorine-containing gas may be introduced into the reaction area by itself or in combination with an inert gas. In either case, the initial concentration of fluorine containing gas is kept low to prevent the reaction from occurring too rapidly, which would cause decomposition of the product, as well as the other problems of prior art direct fluorinations reactions.
As the reaction proceeds, the fluorine or halogen fluoride concentration can be safely increased, because as the reactant molecules become more highly fluorinated, they are able to withstand more fluorine collisions without decomposing. The specific dilution scheme used for the reaction gas depends on the specific reactant, desired product, and other variables.
The perfluorinated analogs of crown ethers are one group of compounds that have not been synthesized before. These ethers have been synthetically inaccessible by conventional reactions of fluorocarbons, and are apparently not capable of synthesis by fluorination on selective fluorination reagents. Because they have not been made previously, there has been no study of the potential uses such compounds might have.